DEC Operators for Barycentric Subdivision

[bosonbaas]

These are some edits to the hodge star and flat operator in order to account for dual meshes which are generated with barycentric subdivision.

This is a WIP and will need significant cleanup, documentation, and tests. Currently this should reduce to the original operators for circumcentric subdivision.

[bosonbaas]

One more thing that will need to be fixed is that currently the flat operator accepts values at the primal vertices instead of surfaces. This was just due to convenience for getting this working with a constant flow-field, so that will need to be reverted.

[epatters]

There are lots of possibilities for setting up a flat operator (Hirani suggests 8!). The one Hirani most discusses is a dual-primal flat (sending dual vector fields to a primal 1-forms), so that's the style I implemented, but if it's also convenient to have a primal-primal flat, we could have that too. No need to restrict to only one kind of flat if, e.g., this kind is more convenient for defining constant flow fields.

[bosonbaas]

This PR is old and was never completed. It would probably be better to start over again on these barycentric subdivision operators, so an issue has been filed #52